TW202003426A - Process and device for the inverted separation of aromatics - Google Patents

Abstract

The present invention relates to a process and to a device for the separation of a feedstock comprising benzene, toluene and C8+ compounds, in which: a toluene column (C10) is fed directly with a C7+ cut resulting from the bottom of a stabilization column (C11) positioned downstream of a transalkylation unit (P4); a C7- cut is withdrawn at the top of the toluene column (C10) and a C8+ cut is withdrawn at the bottom; a benzene column (C9) is fed with the C7- cut resulting from the toluene column (C10); an essentially aromatic cut resulting from an aromatics extraction unit (P1) is injected into the toluene column (C10) separately above the feeding of the C7+ cut or into the benzene column (C9).

Description

Method and device for reverse separation of aromatic compounds

The invention belongs to the field of methods and devices for separating aromatic compounds. The object according to the invention is particularly suitable for aromatic compound complexes (aromatic complex) which need to be carried out by distillation between benzene, toluene and heavier compounds with 8 or more carbon atoms (hereinafter referred to as C8+ compounds) The situation of separation.

Patent FR 2 998 301 B1 describes a method that can save the total energy consumption of fuel and electricity in an aromatic compound device for separation by distillation between benzene, toluene and C8+ compounds. Specifically, the principle of this method is to generate low-pressure steam in certain columns, and use the resulting low-pressure steam as a heat exchange fluid (with or without intermediate compression), for example, for other columns that experience a pressure drop At a lower temperature.

Under the circumstances described above, the first objective of the present invention is to make it possible to reduce the amount of energy required to carry out the separation between benzene, toluene and C8+ compounds.

According to the first aspect, the above objectives and other advantages are obtained by a method for separating raw materials containing benzene, toluene and compounds having 8 or more carbon atoms, which includes at least one recombinant column, In the separation device of an aromatic compound extraction unit and a transalkylation unit, the effluent from these units is separated in the following distillation columns: benzene column, toluene column and stable column. The method includes the following stages : The C7+ fraction produced from the bottom of the stable column positioned downstream of the transalkylation unit is fed directly to the toluene column so that the top product rich in benzene and toluene is extracted from the toluene column, and the rich product with 8 is extracted from the toluene column The bottom product of a compound of one or more carbon atoms, Feeding the benzene column with the top product from the toluene column to extract the benzene-rich top product from the benzene column and the toluene-rich bottom product from the benzene column, and Feed the transalkylation unit with toluene-rich bottom product from the benzene column, The main aromatic fraction produced by the aromatic compound extraction unit is fed to the toluene column, and the feed of the toluene column produced by the aromatic compound extraction unit is separated from the feed of the toluene column produced by the bottom of the stable column And proceed above it, or The benzene column is fed with the main aromatic fraction produced by the aromatic compound extraction unit, which is in the form of a mixture with or separated from the top product from the toluene column.

According to one or more embodiments, the toluene column is additionally fed with the top product from the purification column, which is in the form of a mixture with or separated from the C7+ fraction produced from the bottom of the stabilization column.

According to one or more embodiments, the transalkylation unit is additionally fed with the top product from the purification column, which is in the form of a mixture with or separated from the bottom product from the benzene column.

According to one or more embodiments, the separation device additionally comprises a paraxylene separation unit and a xylene isomerization unit, and the effluents are separated in the following additional distillation columns: xylene column, heavy aromatic compound column, Extraction column, extraction column, purification column, deheptane column and stripping column.

According to one or more embodiments, only the xylene column and the heavy aromatic compound column feed the C9+ aromatic compound to the transalkylation unit.

According to one or more embodiments, the feedstock is fed to the recombinant column to produce a C7-fraction at the top of the recombinant column, and the aromatic compound extraction unit is fed with a C7-fraction to extract paraffin compounds from the C7-fraction and produce The main aromatic fraction.

According to one or more embodiments, the operating conditions of the benzene column are as follows: The temperature at the reboiler is 130°C to 180°C, and the temperature at the condenser is 70°C to 130°C; Pressure: between 0.1 MPa and 0.5 MPa; and The theoretical plates are between 35 and 55.

According to one or more embodiments, the operating conditions of the toluene column are as follows: The temperature at the reboiler is 130°C to 260°C, and the temperature at the condenser is 50°C to 200°C; Pressure: between 0.05 MPa and 1 MPa; and The theoretical plates are between 30 and 55.

According to the second aspect, the above objectives and other advantages are obtained by a device for separating raw materials containing benzene, toluene and compounds having 8 or more carbon atoms, the separation device including at least one recombinant column , An aromatic compound extraction unit and a transalkylation unit, the separation device additionally includes the following columns for distilling the effluent from these units: benzene column, toluene column and stabilization column, The toluene column is suitable for feeding the C7+ fraction produced from the bottom of the stable column positioned downstream of the transalkylation unit, and is suitable for delivering the top product from the toluene column rich in benzene and toluene and rich in 8 The bottom product of the toluene column of more carbon compounds, -The benzene column is suitable for feeding the top product from the toluene column and is suitable for delivering the benzene-rich top product from the benzene column and the toluene-rich bottom product from the benzene column, -The transalkylation unit is suitable for processing toluene-rich bottom products from benzene columns, The toluene column is suitable for feeding the main aromatic fraction produced by the aromatic compound extraction unit, the feed of the toluene column produced by the aromatic compound extraction unit and the toluene column produced by the bottom of the stable column Feed separately and above it, or The benzene column is suitable for feeding the main aromatic fraction produced by the aromatic compound extraction unit to the main aromatic fraction in the form of a mixture with or separated from the top product from the toluene column.

According to one or more embodiments, the toluene column is suitable for feeding the top product from the purification column, which is in the form of a mixture with or separated from the C7+ fraction produced from the bottom of the stabilizing column.

According to one or more embodiments, the transalkylation unit is suitable for feeding the top product from the purification column, which is in the form of a mixture with or separated from the bottom product from the benzene column.

According to one or more embodiments, the separation device additionally includes a paraxylene separation unit, a xylene isomerization unit, and the following additional columns for distilling these effluents: xylene column, heavy aromatic compound column, Extraction column, extraction column, purification column, deheptane column and stripping column.

According to one or more embodiments, the separation device is adapted to feed the raw materials to the recombination column to produce a C7-fraction at the top of the recombination column, and feed the C7-fraction to the aromatic compound extraction unit to remove from the C7- The distillate extracts paraffin compounds and produces the main aromatic distillate.

According to one or more embodiments, the operating conditions of the benzene column are as follows: The temperature at the reboiler is 130°C to 180°C, and the temperature at the condenser is 70°C to 130°C; Pressure: between 0.1 MPa and 0.5 MPa; and The theoretical plates are between 35 and 55.

According to one or more embodiments, the operating conditions of the toluene column are as follows: The temperature at the reboiler is 130°C to 260°C, and the temperature at the condenser is 50°C to 200°C; Pressure: between 0.05 MPa and 1 MPa; and The theoretical plates are between 30 and 55.

The embodiments and other features and advantages of the methods and devices mentioned above will become apparent when reading the following embodiments, which are given for illustrative purposes only and are not limited, and refer to the following drawings.

The present invention relates to the field of methods and devices for separating raw materials containing benzene, toluene, and C8+ (eg, C8 to C10) compounds (which may especially include p-xylene).

The separation method and apparatus according to the present invention can be defined as a series of conversion and separation stages and sections, which are intended to be rich in aromatic compounds (ranging from benzene to aromatic compounds with more than 10 carbon atoms (denoted as C10+ Compounds)) starting materials (eg from catalytic recombination units), separation of benzene/toluene/xylene and/or conversion of toluene into C8+ compounds, and in particular, an aromatic group called xylene with eight carbon atoms The compound, and more specifically, p-xylene. Raw materials rich in aromatic compounds usually exhibit very low to zero levels of sulfur-containing compounds, nitrogen-containing compounds and olefin compounds (eg, according to ASTM D 1159, sulfur content <0.5 ppm (weight) and/or nitrogen content <0.5 ppm (Weight) and/or bromine content <1 g/100 g), because these compounds can affect the performance quality and service life of certain catalysts and molecular sieves used in aromatic compound device units.

The first object according to the invention can be defined as reversing the order of the benzene column and the toluene column and feeding the raw materials separately to the column (according to patent FR 2 998 301 B1, which is directed to the benzene column in the form of a mixture), This is for higher energy efficiency.

In the following embodiments, the term " composite device " is used to denote any refining or petrochemical device containing at least two distillation columns. This definition includes, for example and means a very wide range of FCC gasoline and means for generating from an aromatic fraction of the xylene or meta-xylene apparatus (referred to as "composite means an aromatic compound"). The following embodiments and examples for explaining the separation method and device according to the present invention are given in the case of an aromatic compound device, but it should be clearly understood that the aromatic compound device constitutes only one case of application and does not The method limits the scope of the separation method and device described in this specification.

FIG. 1 depicts a reference method for separating benzene, toluene and C8+ compounds and a schematic diagram of an aromatic compound compounding device.

With reference to FIG. 1, in particular, a series of two columns are described: a benzene column C9 and a toluene column C10. To this series of columns is fed a mixture of the main aromatic C6-C7 fraction produced by the aromatic compound extraction unit P1 and the C7+ fraction produced by the bottom of the column of the stable column C11 downstream of the transalkylation unit P4. The benzene column C9 produces benzene as the final product at the top and the C7+ fraction at the bottom that is passed to the toluene column C10. Toluene was recovered at the top of the toluene column C10, and the C8+ fraction was extracted at the bottom of the toluene column C10.

FIG. 2 depicts a diagram of a separation method and apparatus according to one or more embodiments of the present invention, especially the energy consumption required for separation between benzene, toluene and C8+ compounds compared to the reference method and aromatic compound composite apparatus It is possible to reduce it.

Referring to FIG. 2, in particular, the area of the separation method and apparatus is described, which is adjusted to feed the toluene column (C10) produced by the bottom of the stable column (C11) positioned downstream of the transalkylation unit (P4) C7+ fraction to extract the top product from the toluene column (C10) rich in benzene and toluene, and the bottom product from the toluene column (C10) rich in compounds with 8 or more carbon atoms; towards benzene The column (C9) feeds the top product from the toluene column (C10) to extract the benzene-rich top product from the benzene column (C9) and the toluene-rich bottom product from the benzene column (C9); And the transalkylation unit (P4) is fed with the toluene-rich bottom product from the benzene column (C9). According to one or more embodiments, the toluene column (C10) is also fed with the main aromatic fraction (hereinafter referred to as C6-C7 fraction) produced by the aromatic extraction unit (P1) and the aromatic extraction unit (P1) The feed of the toluene column (C10) produced is separated from the feed of the toluene column (C10) produced from the bottom of the stabilization column (C11) and is carried out above it (downstream thereof). According to one or more embodiments, the C6-C7 fraction produced by the aromatic compound extraction unit (P1) is also fed to the benzene column (C9) as a mixture with the top product from the toluene column (C10) Form or separate from it.

The conversion and separation stages and sections of the separation method and apparatus according to the invention are described in more detail below.

When the goal is only to separate benzene, C8 compounds and optionally toluene from the raw materials, there are only stages or sections C1, P1, C9, C10, P4 and C11. The other sections described below are only useful when it is necessary to separate xylene, and indeed even to maximize p-xylene yield.

Recombinant column C1 transfers the raw material to be processed via line 1 to the first distillation column (denoted as recombinant column C1), which makes toluene and lighter compounds (C7-compound fraction) and heavier compounds (C8 Fractions to C10+ compounds) are separated.

The aromatic compound extraction unit P1 leads the top effluent from the recombinant column C1 to the aromatic compound extraction unit P1 via the line 10.

Via line 81, the toluene and optionally the compound recovered at the bottom of the stripping column C8 are sent to the aromatic compound extraction unit P1.

The aromatic compound extraction unit P1 separates the main aromatic C6-C7 fraction from the product containing paraffin compounds, and the product is transferred to the aromatic compound compounding device via line 13. The preferred solvent used in the aromatic compound extraction unit P1 is N-formylmorpholine (NFM).

Referring to FIG. 1, in the separation section F, the C6-C7 fraction produced by the aromatic compound extraction unit P1 is led to the benzene column C9 via the line 12.

Referring to FIG. 2, in the separation section F, the C6-C7 fraction produced by the aromatic compound extraction unit P1 is led to the benzene column C9 via line 12 or (for purification from some C8 compounds it may contain) to Toluene column C10.

According to one or more embodiments, the aromatic compound extraction unit P1 includes an extractive distillation unit.

The xylene column C2 transfers the C8-C10+ aromatic compounds recovered at the bottom of the column C1 to the xylene column C2 via line 11 in order to make C9 and the heavier (C9+ compound) aromatic compounds and aromatics located downstream Separation of the xylene fraction of the C8 aromatic compound fed into the compound compound unit unit.

The para-xylene separation unit P2 recovers the xylene fraction (that is, the fraction containing C8 aromatic compounds of para-xylene, meta-xylene, o-xylene, and ethylbenzene) at the top of the xylene column C2, and passes it through line 20 It is sent to the para-xylene separation unit P2, which selectively recovers the para-xylene present in the xylene fraction.

The para-xylene separation unit P2 may be a pair suitable for generating, for example, a mixture of para-xylene and a desorbent (referred to as an extract) and a mixture of other C8-aromatic compounds and a desorbent (referred to as a raffinate) Xylene adsorption unit.

The adsorbent used is a molecular sieve dedicated to the adsorption of xylene, that is, it exhibits a particularly high affinity for this compound.

Commonly used adsorbent solids are faujasite-type zeolites formed from siliceous binders, which are exchanged with barium or potassium. The preferred desorbent used is para-diethylbenzene (PDEB).

According to one or more embodiments, the para-xylene separation unit P2 comprises a para-xylene crystallization unit, for example as described in US Patent 3 467 724.

According to one or more embodiments, the para-xylene separation unit P2 includes a combination of a para-xylene adsorption unit and a crystallization unit, as described in, for example, patent EP-B-053 191.

Extraction column C5 This column is used when the separation unit is paraxylene adsorption type. Via line 22, the stream generated by the paraxylene adsorption unit and containing the extract of paraxylene and the desorbent is transferred to the extraction column C5 for separating paraxylene from the desorbent. The desorbent recovered at the bottom of the extraction column C5 is transferred back to the adsorption column via line 51. The paraxylene recovered at the top of the extraction column C5 is sent to the purification column C6.

Purification column C6 transfers the top stream from extraction column C5 via line 50 to purification column C6, which separates toluene (which is partially extracted with para-xylene) from para-xylene.

The generated high-purity p-xylene is recovered at the bottom of the purification column C6, and is transferred as a finished product by pumping via line 61 for storage.

According to one or more embodiments, the top product from purification column C6 is directed to benzene column C9 (line 60) in separation section F.

Referring to FIG. 2, the top product from the purification column C6 may be directed to the benzene column C9 or the toluene column C10 in the form of a mixture with the top stream from the column C10 or via a separate feed. For example, in the form of a mixture with the C7+ fraction produced from the bottom of the stable column C11 (line 112) to purify the top product from some C8 compounds it may contain; and/or directly recycled to the transalkylation unit P4, for example In the form of a mixture with the C7+ fraction extracted at the bottom of the benzene column C9.

The raffinate column C4 transfers the raffinate originating from the para-xylene separation unit P2 to the raffinate column C4 that separates the C8 aromatic compound (raffinate) from the desorbent via the line 23. The desorbent recovered at the bottom of the column C4 is transferred back to the paraxylene adsorption section P2 via line 41.

The raffinate (C8 aromatic compound fraction) is extracted by discharging the side stream, and it is transferred as a raw material of the xylene isomerization unit P3 via the line 40.

Desorbent column ( not shown ) This column is used when the paraxylene separation unit is paraxylene adsorption type. A small portion of the desorbent circulating in the paraxylene adsorption unit is transferred to a desorbent column (not shown) to remove heavy compounds therefrom, otherwise it will accumulate in the loop.

Xylene isomerization unit P3 The xylene isomerization unit P3 is used to convert paraxylene-depleted raw materials into a xylene stream (expressed as "isomerate") under thermodynamic equilibrium.

Any type of catalyst capable of isomerizing hydrocarbons having 8 carbon atoms can be used in the separation method and apparatus according to the present invention. It is preferred to use a dehydrogenated metal (such as platinum, palladium or nickel) and an acidic phase (for example doped alumina, zeolite (such as mordenite, MFI, zeolite Y) or contain such as aluminum phosphate (for example aluminum phosphate AlPO, silicoaluminophosphate (SAPO) acid zeolite or non-zeolitic molecular sieve) catalyst. Therefore, it may be better to use isomerization catalysts containing zeolites of the EUO structure type (such as zeolite EUI, zeolite ZSM 50 or zeolite TPZ3), such as US Patent 4 640 829, EP-B-042 226 or EP-B-051 318 Described in.

The deheptane column C7 transfers the effluent from the xylene isomerization unit P3 via line 42 to the deheptane column C7, which makes the isomer (C8 + aromatic compound) and the top of the deheptane column column C7 The recovered C7-light ends are separated. This C7-fraction is sent to the stripping column C8 via line 71 to separate light compounds from the C7-fraction.

The C8+ fraction formed by xylene and heavier compounds recovered at the bottom of the deheptanizer C7 via line 72 is recycled to the xylene column C2.

In view of the large amount of light (C4-) compounds contained in the deheptane column (C7), the top product from the deheptane column C7 may contain gas phase 70 (mainly composed of light (C4-) compounds) and liquid phase 71, Both are produced by a reflux tank (not shown).

Stripping column C8 feeds stripping column (or stripping column) C8 via the top of deheptane column C7.

The stable C7-fraction is recovered at the bottom of the stripper C8 to be sent to the aromatic compound extraction unit P1 via line 81.

The light (C4-) compound produced from the top of the stripping column is mixed with the light compound from the top of the deheptanizer (line 70) via line 80 and discharged.

The heavy aromatic compound column C3 transfers the C9+aromatic compound recovered at the bottom of the xylene column C2 to the heavy aromatic compound column C3 via the line 21, the heavy aromatic compound column C3 and C10 aromatic compound Heavy compounds such as naphthalene are separated, these heavier compounds may have an adverse effect on the transalkylation catalyst and they are recovered at the bottom via line 31.

The transalkylation unit P4 sends the C9 and C10 aromatic compounds recovered at the top of the heavy aromatic compound column C3 to the transalkylation unit P4 via line 30.

Referring to FIG. 1, C9 and C10 aromatic compounds are mixed with toluene derived from the top of the toluene column C10.

Referring to FIG. 2, C9 and C10 aromatic compounds are mixed with toluene derived from the bottom of the benzene column C9.

The transalkylation unit P4 will generate toluene and C9+ aromatic compounds derived from the recombination column C1 and the isomers derived from the xylene isomerization unit P3 (after passing through the xylene column C2 and the heavy aromatic compound column After C3) conversion to a mixture of xylene and benzene via thermodynamic limiting reaction. According to one or more embodiments, the xylene column C2 and the heavy aromatic compound column C3 provide most (substantially all) C9+ aromatic compounds that are transferred to the transalkylation unit P4.

Any type of transalkylation catalyst can be used in the separation method and apparatus according to the present invention, such as the mordenite or faujasite-based catalyst described in US Patent 3 437 710, or based on the US Patent 5 030 787 MCM-22 or beta zeolite catalyst, or a mordenite and MFI zeolite based catalyst as described in US Patent Application 2012/0065446. These catalysts usually additionally comprise metal compounds preferably selected from the group consisting of rhenium, nickel, cobalt, molybdenum, tungsten, palladium and platinum.

The stabilization column C11 sends the effluent from the transalkylation unit P4 containing benzene, unconverted toluene and C8 (e.g. xylene) and C9+ aromatic compounds via line 102 to the stabilization column C11, which stabilizes the column Compounds lighter than benzene are separated from benzene and heavier aromatic compounds (denoted as C7+ compounds).

The gas leaving the stable column C11 (the reflux tank) is sent to the boundary of the aromatic compound composite device via the line 110.

The unpurified benzene fraction is discharged as a side stream and transferred to the stripping column C8 via line 111 so that light compounds can be separated from the fraction.

According to one or more embodiments, partial condensation of the top gas from the stabilization column C11 is achieved by means of a cooling tower (optionally followed by a water cooler).

Separation section F The separation section F includes a benzene column C9 and a toluene column C10.

According to the reference method and the benzene column C9 of the aromatic compound compounding device, refer to FIG. 1, the C6-C7 fraction produced by the aromatic compound extraction unit P1 (line 12) and the C7+ fraction produced by the bottom of the stable column C11 (line 112) Mix and transfer to benzene column C9. The benzene as the final product is extracted from the benzene column C9 via line 90 at the top of the benzene column C9. The C7+ fraction extracted at the bottom of the benzene column C9 is led to the toluene column C10 via line 91.

According to the reference method and the toluene column C10 of the aromatic compound compounding device, referring to FIG. 1, the C7+ fraction produced from the bottom of the benzene column C9 is fed to the toluene column C10. The toluene recovered at the top of the toluene column C10 is introduced via line 100 as the raw material for the transalkylation unit P4. The C8+ fraction extracted at the bottom of the column C10 is recycled to the xylene column C2 via line 101.

According to the toluene column C10 of the separation method and apparatus of the present invention, referring to FIG. 2, the toluene column C10 is fed with the C7+ fraction generated from the bottom of the stable column C11 (line 112). The top product from the toluene column C10 is a C7-compound-rich fraction (eg, main toluene + C6-compound), and the bottom product is a C8+-fraction enriched in aromatic compounds having 8 carbon atoms.

The C8+ fraction extracted at the bottom of the toluene column C10 (that is, the bottom product from the toluene column C10 rich in compounds having 8 or more carbon atoms) is recycled to the xylene column C2 via line 101. The xylene column separates C9+ and heavier compounds from the C8 aromatic compound fraction fed to the paraxylene separation unit.

According to one or more embodiments, the C6-C7 fraction produced by the aromatic compound extraction unit P1 is transferred to the toluene column C10 in a separate manner and above the C7+ fraction feed produced from the bottom of the stable column C11.

According to one or more embodiments of the present invention, since the effluent produced at the top of the purification column C6 may have an extremely low flow rate compared to the other two streams treated by the separation section F, the effluent is The C7+ fractions produced from the bottom of column C11 are mixed. It is also possible to feed the stream generated from the top of the purification column C6 to any other location in the separation section F. For example, the top of the purification column C6 can be recycled to the benzene column C9 or directly to the transalkylation unit P4. For example, a mixture comprising the bottom product from the benzene column C9 and the top product from the purification column C6 can be fed to the transalkylation unit P4.

According to one or more embodiments, the operating conditions of the toluene column are as follows: The temperature at the reboiler is 130°C to 260°C, and the temperature at the condenser is 50°C to 200°C; Pressure: between 0.05 MPa and 1 MPa; and The theoretical plates are between 30 and 55.

According to the benzene column C9 of the separation method and apparatus of the present invention, referring to FIG. 2, the C7-distillate extracted at the top of the toluene column C10 (that is, the top product from the toluene column rich in benzene and toluene) via line 91 Lead to benzene column C9.

According to one or more embodiments of the present invention, for example, when the C6-C7 fraction produced by the aromatic compound extraction unit P1 contains very little C8+ (for example, in the C6-C7 fraction, C8+ <1% by weight, preferably, <0.5 % By weight, and even better, <0.3% by weight), the C6-C7 fraction produced by the aromatic compound extraction unit P1 is led to the benzene column C9 downstream of the toluene column C10 (presenting the top of the toluene column C10 Or in a separate mixture). According to one or more embodiments, the feed of the benzene column C9 produced by the aromatic compound extraction unit P1 is separated from the feed produced by the top of the toluene column C10 and is preferably performed above (downstream thereof).

Starting from the benzene column C9, the benzene-rich top product as the final product is extracted via line 90. According to one or more embodiments, the benzene-rich product is extracted by discharging the side stream. According to one or more embodiments, light and non-condensable compounds are discharged through the steam stream at the top of the column (line 92). The toluene-rich bottom product from the benzene column C9 is led to the transalkylation unit P4 via line 100.

According to one or more embodiments, the operating conditions of the benzene column are as follows: The temperature at the reboiler is 130°C to 180°C, and the temperature at the condenser is 70°C to 130°C; Pressure: between 0.1 MPa and 0.5 MPa; and The theoretical plates are between 35 and 55.

In FIGS. 1 and 2, for simplicity, the reflux section, reflux tank, or condenser are not shown; any known condensation means (eg, cooling tower and/or water cooler) may be used.

EXAMPLES In each example, the following two raw materials were fed to the separation section F:-Raw material 1: C6-C7 fraction produced by the aromatic compound extraction unit P1; and-Raw material 2: C7+ produced from the bottom of the stable column C11 Distillate.

In each example, the top of the purification column C6 was directly recycled to the transalkylation unit P4.

Example 1 The composition of the two feedstocks (feedstock 1 and feedstock 2) of separation section F is shown in Table 1.

According to the composition of Table 2, each fraction discharged from the separation section F is divided into products rich in benzene, toluene and C8+ compounds.

Evaluation of four fractionation configurations: -Configuration 1 (according to the reference separation method and device): feeding a mixture of two raw materials to the benzene column. The bottom of the benzene column feeds the toluene column. -Configuration 2 (comparison): feeding two raw materials to the benzene column (introduced separately into the column). The bottom of the benzene column feeds the toluene column. -Configuration 3 (comparison): feeding a mixture of two raw materials to the toluene column. The top of the toluene column is fed to the benzene column. -Configuration 4 (according to the separation method and device according to the invention): feeding two raw materials to the toluene column (introduced separately into the column). Feed 1 is fed above feed 2. The top of the toluene column is fed to the benzene column.

Optimize the feed position in each of the configurations to minimize the reboiling energy consumption of each of the columns.

The geometry and energy consumption of each of the configurations are shown in Table 3.

It was surprisingly noted that compared to the reference example, significant (more than 10%) energy savings can be obtained only by reversing the order of the column and by introducing two raw materials separately (configuration 4 according to the invention). Simple column reversal (configuration 3) or separate introduction of the two feeds (configuration 2) separately from each other cannot achieve significant energy savings.

In this example, when the benzene column C9 is downstream of the toluene column C10, the C6-C7 fraction produced by the aromatic compound extraction unit P1 is directly directed to the benzene column C9 because of its C8+ compound content (767 kg/ Hour) greater than the C8+ compound content (267 kg/hour) (this is expected from the bottom product of the toluene column C10).

Example 2 The composition of two raw materials in the separation section (F) of benzene, toluene and C8+ compounds is shown in Table 4.

In this example, in the pattern where the benzene column C9 according to the present invention is located downstream of the toluene column C10, the content of the C8+ compound (192 kg/h) in the raw material 1 is such that the C6/C7 fraction (from aromatic compounds) It is possible to direct the raw material 1 produced by the separation unit P1 to the benzene column C9.

Evaluation of three fractionation configurations: -Configuration 1 (according to the reference separation method and device): feeding a mixture of 2 raw materials to the benzene column. The bottom of the benzene column feeds the toluene column. -Configuration 5 (according to the invention): feed the raw material 2 to the toluene column only. Mix raw material 1 at the top of the toluene column. This mixture is fed to the benzene column. -Configuration 6 (according to the present invention): feed the raw material 2 to the toluene column only. Feed 1 and the top of the toluene column are fed separately to the benzene column.

According to the composition of Table 5 (according to configuration 1) and according to the composition of Table 6 (according to configurations 5 and 6), the distillate discharged from the separation section F is divided into products rich in benzene, toluene and C8+ compounds respectively.

The content of the C8+ compound in the raw material 1 is sufficiently low so that the same C8+ compound content in the configuration 1 can be obtained in the toluene-rich products in the configurations 5 and 6 (268 kg/h).

The feed location is optimized in each of the configurations in order to minimize the reboil energy consumption in each of the columns.

The geometry and energy consumption in each of the configurations are shown in Table 7.

Compared to configuration 1 according to the reference separation method and device, configurations 5 and 6 according to the invention are more energy efficient.

1‧‧‧ pipeline 10‧‧‧ pipeline 11‧‧‧ pipeline 12‧‧‧ pipeline 13‧‧‧ pipeline 20‧‧‧ pipeline 21‧‧‧ pipeline 22‧‧‧ pipeline 23‧‧‧ pipeline 30‧‧‧ pipeline 31‧‧‧ pipeline 40‧‧‧ pipeline 41‧‧‧ pipeline 42‧‧‧ pipeline 50‧‧‧ pipeline 51‧‧‧ pipeline 60‧‧‧ pipeline 61‧‧‧ pipeline 70‧‧‧ pipeline 71‧‧‧ pipeline 72‧‧‧ pipeline 80‧‧‧ pipeline 81‧‧‧ pipeline 90‧‧‧ pipeline 91‧‧‧ pipeline 92‧‧‧ pipeline 100‧‧‧ pipeline 101‧‧‧ pipeline 102‧‧‧ pipeline 110‧‧‧ pipeline 111‧‧‧ pipeline 112‧‧‧ pipeline C1‧‧‧recombinant column C2‧‧‧xylene column C3‧‧‧Heavy aromatic compound column C4‧‧‧Raffinate column C5‧‧‧Extraction column C6‧‧‧Purification column C7‧‧‧Deheptane Tower C8‧‧‧Stripping Tower C9‧‧‧Benzene column C10‧‧‧Toluene column C11‧‧‧stable column F‧‧‧ Separation section P1‧‧‧ aromatic compound extraction unit P2‧‧‧paraxylene separation unit P3‧‧‧xylene isomerization unit P4‧‧‧Transalkylation unit

FIG. 1 depicts a diagram of an aromatic compound composite device including a reference separation section F for separating benzene, toluene, and C8+ compounds. Fig. 2 depicts a diagram of an aromatic compound compounding device comprising a separation section F according to the invention for separating benzene, toluene and C8+ compounds.

1‧‧‧ pipeline

10‧‧‧ pipeline

11‧‧‧ pipeline

12‧‧‧ pipeline

13‧‧‧ pipeline

20‧‧‧ pipeline

21‧‧‧ pipeline

22‧‧‧ pipeline

23‧‧‧ pipeline

30‧‧‧ pipeline

31‧‧‧ pipeline

40‧‧‧ pipeline

41‧‧‧ pipeline

42‧‧‧ pipeline

50‧‧‧ pipeline

51‧‧‧ pipeline

60‧‧‧ pipeline

61‧‧‧ pipeline

70‧‧‧ pipeline

71‧‧‧ pipeline

72‧‧‧ pipeline

80‧‧‧ pipeline

81‧‧‧ pipeline

90‧‧‧ pipeline

91‧‧‧ pipeline

92‧‧‧ pipeline

100‧‧‧ pipeline

101‧‧‧ pipeline

102‧‧‧ pipeline

110‧‧‧ pipeline

111‧‧‧ pipeline

112‧‧‧ pipeline

C1‧‧‧recombinant column

C2‧‧‧xylene column

C3‧‧‧Heavy aromatic compound column

C4‧‧‧Raffinate column

C5‧‧‧Extraction column

C6‧‧‧Purification column

C7‧‧‧Deheptane Tower

C8‧‧‧Stripping Tower

C9‧‧‧Benzene column

C10‧‧‧Toluene column

C11‧‧‧stable column

F‧‧‧ Separation section

P1‧‧‧ aromatic compound extraction unit

P2‧‧‧paraxylene separation unit

P3‧‧‧xylene isomerization unit

P4‧‧‧Transalkylation unit

Claims (15)

A method for separating raw materials containing benzene, toluene and compounds having 8 or more carbon atoms, which includes at least one recombinant column (C1), an aromatic compound extraction unit (P1) and a conversion In the separation device of the alkylation unit (P4), the effluent from these units is separated in the following distillation columns: benzene column (C9), toluene column (C10) and stable column (C11), the method The following stages are included: The toluene column (C10) is fed directly with the C7+ fraction generated from the bottom of the stabilizing column (C11) positioned downstream of the transalkylation unit (P4) to extract benzene-rich from the toluene column (C10) And the top product of toluene, and the bottom product rich in compounds with 8 or more carbon atoms is extracted from the toluene column (C10), The top product from the toluene column (C10) is fed to the benzene column (C9) in order to extract the benzene-rich top product from the benzene column (C9) and from the benzene column (C9) Toluene-rich bottom products, and The toluene-rich bottom product from the benzene column (C9) is fed to the transalkylation unit (P4), The toluene column (C10) is fed with the main aromatic fraction produced by the aromatic compound extraction unit (P1), and the toluene column (C10) produced by the aromatic compound extraction unit (P1) is fed Separate from the feed of the toluene column (C10) generated from the bottom of the stable column (C11) and proceed above it, or The main aromatic fraction produced by the aromatic compound extraction unit (P1) is fed to the benzene column (C9) in the form of a mixture with the top product from the toluene column (C10) Or separate from it. The separation method according to claim 1, wherein the toluene column (C10) is additionally fed with the top product from the purification column (C6), and the top product is present as the C7+ fraction produced from the bottom of the stable column (C11) Or separate from it. The separation method according to claim 1, wherein the transalkylation unit (P4) is additionally fed with the top product from the purification column (C6), which is a mixture with the bottom product from the benzene column (C9) Form or separate from it. The separation method according to any one of claims 1 to 3, wherein the separation device additionally comprises a paraxylene separation unit (P2) and a xylene isomerization unit (P3), and the effluents are in the following additional distillation columns Separation: xylene column (C2), heavy aromatic compound column (C3), raffinate column (C4), extraction column (C5), purification column (C6), deheptane column (C7) And stripping tower (C8). The separation method according to claim 4, wherein only the xylene column (C2) and the heavy aromatic compound column (C3) feed the C9+ aromatic compound to the transalkylation unit (P4). The separation method according to any one of claims 1 to 3, wherein the raw material is fed to the recombinant column (C1) so as to produce a C7-fraction on top of the recombinant column (C1), and the aromatic compound The extraction unit (P1) feeds the C7-fraction to extract paraffin compounds from the C7-fraction and produce the main aromatic fraction. For the separation method of any one of claims 1 to 3, the operating conditions of the benzene column (C9) are as follows: The temperature at the reboiler is 130°C to 180°C, and the temperature at the condenser is 70°C to 130°C; Pressure: between 0.1 MPa and 0.5 MPa; and The benzene column (C9) contains between 35 and 55 theoretical plates. For the separation method of any one of claims 1 to 3, the operating conditions of the toluene column (C10) are as follows: The temperature at the reboiler is 130°C to 260°C, and the temperature at the condenser is 50°C to 200°C; Pressure: between 0.05 MPa and 1 MPa; and The toluene column (C10) contains between 30 and 55 theoretical plates. A device for separating raw materials containing benzene, toluene and compounds having 8 or more carbon atoms, the separation device includes at least one recombinant column (C1), an aromatic compound extraction unit (P1) and a Transalkylation unit (P4), the separation device additionally contains the following columns for distilling the effluent from these units: benzene column (C9), toluene column (C10) and stabilization column (C11), The toluene column (C10) is suitable for feeding the C7+ fraction produced from the bottom of the stable column (C11) located downstream of the transalkylation unit (P4), and is suitable for delivering benzene and toluene-rich The top product of the toluene column (C10) and the bottom product from the toluene column (C10) rich in compounds having 8 or more carbon atoms, The benzene column (C9) is suitable for feeding the top product from the toluene column (C10), and is suitable for delivering the benzene-rich top product from the benzene column (C9) and from the benzene tube Column (C9) bottom product rich in toluene, and The transalkylation unit (P4) is suitable for processing the toluene-rich bottom product from the benzene column (C9), The toluene column (C10) is suitable for feeding the main aromatic fraction produced by the aromatic compound extraction unit (P1), and the toluene column (C10) produced by the aromatic compound extraction unit (P1) Is fed separately from and above the feed of the toluene column (C10) produced from the bottom of the stable column (C11), or Wherein the benzene column (C9) is suitable for feeding the main aromatic fraction produced by the aromatic compound extraction unit (P1) to the top product from the toluene column (C10) Or separate from it. The separation device according to claim 9, wherein the toluene column (C10) is suitable for feeding the top product from the purification column (C6) to the top product as the product produced from the bottom of the stable column (C11) The C7+ fraction is in the form of a mixture or separate from it. The separation device according to claim 9, wherein the transalkylation unit (P4) is adapted to feed the top product from the purification column (C6) to the bottom product from the benzene column (C9) Or separate from it. The separation device according to any one of claims 9 to 11, which additionally comprises a paraxylene separation unit (P2), a xylene isomerization unit (P3) and the following additional columns for distilling these effluents: two Toluene column (C2), heavy aromatic compound column (C3), raffinate column (C4), extraction column (C5), purification column (C6), deheptane column (C7) and stripping Tower (C8). The separation device according to any one of claims 9 to 11, wherein the recombinant column (C1) is adapted to feed the raw material thereto to produce a C7-fraction on top of the recombinant column (C1), and the aroma The group compound extraction unit (P1) is adapted to feed the C7-fraction to it to extract paraffin compounds from the C7-fraction and produce the main aromatic fraction. The separation device according to any one of claims 9 to 11, wherein the benzene column (C9) is suitable for use under the following operating conditions: The temperature at the reboiler is 130°C to 180°C, and the temperature at the condenser is 70°C to 130°C; Pressure: between 0.1 MPa and 0.5 MPa; and The benzene column (C9) contains between 35 and 55 theoretical plates. The separation device according to any one of claims 9 to 11, wherein the toluene column (C10) is suitable for use under the following operating conditions: The temperature at the reboiler is 130°C to 260°C, and the temperature at the condenser is 50°C to 200°C; Pressure: between 0.05 MPa and 1 MPa; and The toluene column (C10) contains between 30 and 55 theoretical plates.

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